Ned, your window stop has gone
how do i know? because i had to fix mine at the roadside yesterday
ok, not sure if this is the preferred method, but its what i did.......
remove the door card - one screw in the interior handle escutcheon, two in the door pull, one in the top front corner, two on the back edge. pull out at the bottom, then slide off to the rear, not forgetting the lock pin.
now, you will see a cut out to the rear of the door, look in there and slightly to the front at the bottom, you will see that the mechanism is toughing the bottom of the door. if you watch carefully now whilst operating the switch, you'll see the motor trying ti lift ther window, but all it does is flex the door
remove the speaker (two screws top, one bottom) look inside and see if you can see the broken / missing stop. ensure it isn't janmmed in anything.
so, you will see the window at the bottom has a sort of curved cut out. get some strong gloves on, and try to pull the window up from this cut whilst operating the switch.
BE CAREFUL!!!
it will come up with a bang, and let go of the switch when it does. it will take some pulling, so be warned!
not saying it is the RIGHT way, just the way i managed last night in an emergency on my way to work
next look for my thread on door cards, and find the link someone posted for replacing the window stops.
note: brown and gammons sell them cheaper than ebay
hope it helps
Lee